The use of heating elements in flooring provides a combination of beauty and comfort. Heated floors in cool areas of a building can provide supplemental heat to the space that is evenly distributed. In homes, warmed floors in a bathroom are kind to an occupant's feet, especially on a cold winter morning.
Several techniques are known to create heated floors. In some applications, heating elements are installed under the subfloor, between floor joists. Using this technique, the heating elements warm the air space under the subfloor, the subfloor and the decorative floor, as well as any mastic, grout or underlayment that may be present. A relatively small percentage of the power used to generate heat actually comes through to the top surface of the decorative floor to be enjoyed by the room occupants. This technique also cannot be used during a remodeling project unless a homeowner is willing to replace the subfloor or ceiling, which is an expensive project.
Heating wires can be embedded in a mortar layer. A second mortar layer is applied to hold ceramic tiles in place. Wires are placed on the subfloor in a custom configuration. The mortar must be sufficiently thick to cover the wires, changing the depth of the floor. Finally, special precautions must be taken by the applicators not to scratch or nick the wires while applying the second layer of mortar. Installation of this type of system is laborious and expensive.
Woven wire mesh heaters having no busses are made whereby thin wires are woven into a mesh mat. The mat can be placed under a laminate floor or under a subfloor. However, these mats must be custom made to fit odd-sized spaces and cannot be altered at the job site. This increases the cost of the heaters and installation, and makes the process of changing the heater layout during installation significantly more difficult.
Polymer-based heaters are made using electrically resistive plastics. A conductive bus on either side of the resistance heaters completes the circuit. The result is a cuttable heating surface; however currently available products exhibit significant thickness.
Conductive ink-based heaters are made from resistive inks printed on plastic sheets. A conductive bus on either side of the resistance heaters completes the circuit. A second plastic sheet is then placed over the circuit to protect the heating elements. The result is a thin, flexible, cuttable heating surface. Conductive ink-based are known for use under laminate floors, where they lay unattached in the space between the floor boards and the subfloor or, in the case of a remodel, an old floor. The plastic sheets that protect the device provide a poor surface for adhesion of ceramic tiles.
Thus, it would be advantageous to be able to utilize a polymer-based heater under ceramic tiles if a system could be devised where there is the proper adhesion between the heater and the tile. The flooring system should be inert to water penetration for use in wet environments, such as a kitchen or bathroom. Further, the system should be cuttable in the field, allowing the exact shape of the heater to be varied as it is being installed and to minimize cost.